Electrophotographic material based on amorphous silicon@ doped with boron@ - or other gp. three element with same ratio of dopant to carbon in barrier and photoconductive layers for low dark decay and high contrast

摘要

Electrophotographic material has an electroconductive substrate (I), a blocking layer (II) of amorphous material contg. Si, H and C atoms and a photoconductive layer (III) of hydrogenated amorphous Si. (III) contains C atoms; (II) and (III) are doped with a gp. III elements. The ratio of the fractions of C and gp. III atoms in (II) and (III) is the same. The ratio of C and gp. III atoms is 10-50. (II) contains 0.5-5 atom-% C, whilst the C/Si ratio in (III) is 2 x 10 power 3 minus 3 to 8 x 10 power 3 minus 3. (II) is 0.05-0.3, pref. ca. 0.2 microns thick and (III) 10-50 microns thick. The distribution of C in (III) is irregular and pref. decreases in the vertical direction from (II), so that it is 10-50 times smaller at the outside than at the boundary with (II). (III) is has a top coat (IV) of amorphous material contg. Si, C and H, pref. contg. 40-99 atom-% C and 20-40 atom-% H, which has an energy band gap of 2-2.3 eV and is 0.05-0.3, pref. 0.1-0.2 microns thick. (IV) is also doped with a gp. II element, the ratio of C to gp. III atoms pref. being the same as in (III). The gp. III element pref. is B and the prod. of the layer thickness and B concn. in (II) pref. is 3 x 10 power13 to 3 x 10 power15 cm2. ADVANTAGE - This compsn. ensures little dark decay in conjunction with high contrast.